Signs of a divided party were apparent at the Democratic National Convention on Monday, as Bernie Sanders supporters loudly booed whenever Hillary Clinton's name was mentioned.

The Vermont senator's supporters are angry over recently leaked emails that show Democratic Party leaders favoring Clinton before the primaries were concluded. At a Florida delegation breakfast, Democratic party chair Debbie Wasserman Schultz was heckled by Sanders' loyalists. It was her first time speaking publicly since announcing her resignation over the leaked emails.

Clinton supporters hope the convention will eventually become a show of party unity.

"This is democracy at its best," said delegate Wendy Greuel, the former Los Angeles city controller and a Clinton supporter. "Sometimes it's messy and not necessarily as clear and clean as you like. But most importantly what you have is a roomful of people who are supporting the Democratic Party and supporting Hillary Clinton."

Bernie Sanders tried to calm tensions among his delegates, but some weren't in a listening mood.